1. Technical Field
This invention relates to the art of joining workpiece materials by solder (or braze) fluxed to the joint area; and more particularly to joining metal plys to a tube array with one or more of increased accuracy, increased reliability, more economy and less time.
2. Discussion of the Prior Art
Large scale soldering of sheet metal to tubes in a heat exchanger or condenser is today carried out by using individual solder rings which are individually slipped around each tube and stationed adjacent the joint area (see U.S. Pat. No. 4,759,405). It is extremely difficult to control thousands of these small rings to achieve reliable placement; often these rings are each laboriously and mechanically nibbed or clinched to prevent them from falling off or being misplaced.
The prior art has attempted to substitute flat foil solder sheets for individual solder rings; the sheets are saddled around or staked to a tube array (see U.S. Pat. Nos. 4,327,800 and 3,710,473). Unfortunately, such techniques are not only slow due to the necessity for piercing, but do not provide sound solder joints because flux must be eliminated or, if used, the flux weepage along the inside of the sheet openings is not precisely controlled. The prior art has also attempted to gang solder rings on a water soluble adhesive strip for ease of handling, but such adhesive strip fails to eliminate the need for mechanical nibbing and does not contemplate flux weepage control along the interior of the rings (see U.S. Pat. No. 4,842,184).